Aortic Regurgitation and Other Complications

Aortic regurgitation may develop as a result of a small ventricular septal defect located in the membranous septum, below the crista supraventricularis and just beneath the aortic valve. Subpulmonary, or supracristal defects, lie above the crista supraventricularis, just below the pulmonary valve. They may also relate closely to aortic valve and may be complicated by aortic regurgitation. High velocity flow through the defect may create forces that pull the cusp of the aortic valve into the defect, thereby, preventing the valve from closing completely. So-called prolapse of an aortic valve cusp may become progressively worse with time. Prolapse of an aortic cusp into a ventricular septal defect can partially obstruct the defect and, therefore, mark the true size of the defect. Aortic regurgitation, when it occurs, almost always begins in early childhood. Its presence often indicates need for surgical repair of both the defect and the valve. Defects in the muscular septum do not cause aortic regurgitation.

Infective endocarditis is another serious complication of a small ventricular septal defect. The most frequent causative organisms are Streptococcus viridans and Staphylococcus aureous. Asymptomatic bacteremia as may occur, for example, with dental infection and dental treatment, represents a potential source for introduction of the organism. There is no effective drug therapy to either prevent or reduce the risk of infective endocarditis. It is important, therefore, to maintain good dental health.

Another complication in an infant or young child with an apparently uncomplicated small ventricular septal defect is the development over several years of discreet right ventricular infundibular obstruction. The obstruction is due to muscular hypertrophy of the structures surrounding the entrance to the infundibulum. It represents an additional heart defect and it is not caused by the presence of a ventricular septal defect. A slowly progressive condition, it usually requires surgical correction. The combination of discreet infundibular obstruction and a small ventricular septal defect should not be confused with tetralogy of Fallot, a condition in which the ventricular septal defect always is large.